Speed limiter

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frostbite

Active Member
Joined
Oct 5, 2014
Messages
201
Location
Cheshire
Car
C43 AMG, 96 Jeep Cherokee 2.5, Triumph Explorer and Thruxton
I'm not after going faster than the 155mph my car is supposed to be limited to, more trying to understand a possible fault. How does the speed limiter work on a C43 AMG, what tells the ECU to stop whatever would make the car exceed 155mph?
Giving it some beans the other day, in the safest of manners of course, the car just refused to go faster than a lot of tens of mph less than 155mph. it got to where it decided was today's limit quickly enough, just no more.
On my list of jobs anyway, is fuel filter change, compression test and coil/lead spark voltage test (all plugs replaced a short while ago - as was the MAF). Don't think it's compression, as no other symptom for that and no gradual reduction in the 'limit'. Is there a possible ECU issue or some sensor somewhere?

Thanks..
 
Just how many beans did your bean counter find before it stopped? either way, get it on star with a good indie to diagnose where your missing beans are
 
I'm not after going faster than the 155mph my car is supposed to be limited to, more trying to understand a possible fault. How does the speed limiter work on a C43 AMG, what tells the ECU to stop whatever would make the car exceed 155mph?
Giving it some beans the other day, in the safest of manners of course, the car just refused to go faster than a lot of tens of mph less than 155mph. it got to where it decided was today's limit quickly enough, just no more.
On my list of jobs anyway, is fuel filter change, compression test and coil/lead spark voltage test (all plugs replaced a short while ago - as was the MAF). Don't think it's compression, as no other symptom for that and no gradual reduction in the 'limit'. Is there a possible ECU issue or some sensor somewhere?

Thanks..

Did you have an orange light on the end of your cruise control stalk?. If so, you have probably set your own limit. Press it in, and when light has gone out, it should go all the way to 155 (assuming it has the same system as most mercs).

Neil
 
Checked through the manual today and found out the car has a 'permanent' speed limiter that can be set while the car is stationary and with the engine off and also doesn't show up anywhere with lights or displays etc. Cleared that up to erase any 'permanent limit' that might have been in there, although I don't think it had a 'permanent limit' set.
Took her for a spin... first blast she topped out at 'a speed'. so I eased off, slowed up and then powered up again, this time topped out at 'a speed' that was 20 mph faster than the first one, though still nowhere near the factory limit.
Back to basics I think before I go too deep, fuel filter and ignition lead/coil checks...
 
i have read that limiter is in 7th gear in some auto boxes, if you have an auto try put it in manual mode and leave it in 6th. a remap can also remove the limiter if you desire.
 
completley ignore the gearbox sentence then ;)
 
Yes, I need to get it plugged in to a 'Star' thingy somewhere. Car's parked up in the barn now, with all its upholstery and rear seats out, waiting for love in the form of some metal inert gas stuff and bits of steel sheet. Once I have a solid body (the car, not me), I'll get stick into the tune.. Thanks for all the posts!
 

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